1. Field of the Invention
The present invention generally relates to thermal printers and apparatuses having a thermal printer, and more particularly, to a thermal printer in which a platen roller is detachable from a frame.
2. Description of the Related Art
Regarding thermal printers mounted in hand-held devices and POS terminals, a clamshell type that allows easy setting of a paper roll is becoming the mainstream. In the clamshell type, when a cover is rotated and closed, a platen roller is pressed against a thermal head via paper and is fit and fixed to a frame. Thus, it is necessary to provide a lock mechanism so that the fixed platen roller not be easily separated from the frame.
FIG. 1 shows a thermal printer 10 of a conventional clamshell type. In FIG. 1, the thermal printer 10 includes a frame 11, a platen roller 12, a thermal head 13, a paper roll 14, paper 15 (a part of the paper roll 14), a lock arm 16, a cam 17, an operation lever 18, and a spring 19.
The platen roller 12 is moved downward from above, and pressed against the thermal head 13 via the paper 15. On this occasion, a shaft 12a of the platen roller 12 provided at an end of the platen roller 12 is fit into a U-shaped slot 11a of the frame 11 and locked by the lock arm 16.
For setting a new paper roll 14, an operator operates the operation lever 18 so as to rotate the cam 17 and rotate the lock arm 16 for a little in the clockwise direction. Consequently, the lock of the shaft 12a is released (for example, refer to Japanese Laid-Open Patent Application No. 2000-318260, paragraph No. 0015, FIG. 2).
The thermal printer 10 shown in FIG. 1 is additionally provided with three dedicated components, that is, the lock arm 16, the cam 17, and the operation lever 18, in order to lock and release the platen roller 12. Thus, there is a problem in that the increase in the number of components increases the manufacturing cost, the assembly processes, and the size and weight of the thermal printer.
It is a general object of the present invention to provide an improved and useful thermal printer, and an apparatus having the thermal printer, in which the above-mentioned problems are eliminated.
In order to achieve the above-mentioned object, according to one aspect of the present invention, there is provided a thermal printer that includes:
a thermal head;
a platen roller;
a frame having platen roller receiving parts that receive the platen roller in a detachable manner; and
a thermal head supporting member to which the thermal head is fixed, the thermal head supporting member being operatively coupled to the frame,
the thermal head supporting member including platen roller lock parts that lock the platen roller received by the platen roller receiving parts so as to resist or prevent the platen roller from exiting the platen roller receiving part.
Accordingly, components dedicated to locking the platen roller are not required, which is advantageous for reducing the size of a thermal printer. Moreover, since the number of assembly processes is decreased, it is possible to reduce manufacturing costs.
Also, in a thermal printer, the thermal head supporting member may include platen roller lifting parts that move the platen roller in the direction in which the platen roller exits the platen roller receiving parts when the thermal head is moved in the direction in which the thermal head is separated from the platen roller.
Accordingly, components dedicated to lifting (pushing up) the platen roller in the direction in which the platen roller exits the platen roller receiving parts are not required, which is advantageous for reducing the size of a thermal printer. Moreover, the number of assembly processes is decreased. Thus, it is possible to reduce manufacturing costs.
In addition, in a thermal printer, the thermal head supporting member may include an operation part that displaces the thermal head in a direction in which the thermal head is separated from the platen roller.
Accordingly, it is possible to simplify the construction of a part operated so as to displace the thermal head supporting member.
Further, the thermal head supporting member may include a head pressure biasing spring portion that biases head pressure whereby the thermal head presses the platen roller.
Accordingly, head pressure biasing spring members are not required, which is advantageous for reducing the size of a thermal printer. Moreover, the number of assembly processes is decreased. Thus, it is possible to reduce manufacturing costs
Additionally, a thermal printer may further include:
a head pressure biasing spring member for pressing the thermal head supporting member so as to bias head pressure whereby the thermal head presses the platen roller, and
the head pressure biasing spring member may include a spring portion that is pressed and deflected by the platen roller received in the platen roller receiving parts, and when the lock of the platen roller is released, restored so as to move the platen roller in the direction in which the platen roller exits the platen roller receiving part.
Accordingly, it is possible to realize, with a small number of components, a thermal printer in which the platen roller pops up when the lock of the platen roller is released.
Furthermore, according to another aspect of the present invention, there is provided an apparatus that includes:
a thermal printer including:
a thermal head;
a platen roller;
a cover supporting the platen roller, the cover being rotatably opened and closed;
a frame having platen roller receiving parts that receive the platen roller in a detachable manner, the platen roller being received by the platen roller receiving parts when the cover is closed; and
a thermal head supporting member to which the thermal head is fixed, the thermal head supporting member being operatively coupled to the frame,
the thermal head supporting member including platen roller lock parts that lock the platen roller received by the platen roller receiving part so as to resist or prevent the platen roller from exiting the platen roller receiving part.
Accordingly, since the size of the thermal printer is reduced, the size of the apparatus is also reduced.
Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the drawings.